The invention is directed to a rotary wall deslagger for cleaning boilers and is of the type comprising a cleaning fluid flower nozzle mounted on a rotatable lance tube which is advanced into an operative position within the boiler and retracted from such position when not in use.
In the operation of boilers, the burning of combustible fuels results in a gradual build-up over a period of time of a layer of slag on the boiler walls. It is therefore necessary to periodically clean the heated surfaces of the boiler to deslag such surfaces. The removal of slag properly maintains the heat conduction efficacy of the boiler at an optimum level, thereby insuring the most efficient utilization of available fuel supplies. Typically, the boiler surfaces are cleaned by inserting a rotatable lance tube, mounting a front nozzle, into the combustion space of the boiler and projecting a cleaning fluid such as steam, air and/or water from the nozzle against the surfaces to be cleaned. The lance tube is retracted from the boiler when not in use and held outside the hot and possibly damaging combustion zones of the boiler to protect the deslagging apparatus from the deleterious effects of the combustion process during the relatively long periods of time that the deslagger is inoperative.
Accordingly, the prior art has proposed many apparatuses for advancing, retracting, rotating and discharging a cleaning fluid through a rotatable lance tube. It has been an objective of those skilled in the art to accomplish a fast and efficient transverse and rotational motion for the tube and to coordinate a valve operation for cleaning fluid discharge with lance movement to achieve the best possible cleaning action with the fluid discharge. A particular problem associated with rotary deslaggers has been premature cleaning fluid discharge whereby the cleaning fluid reaches the nozzle prior to nozzle rotation. This results in a highly inefficient use of the cleaning fluid and over exposure of certain portions of the boiler interior to the cleaning fluid.
It is a primary objective of the present invention to provide a new and improved rotary boiler wall deslagger which incorporates a highly effective and straightforward mechanism for advancing and retracting the lance tube and for initiating fluid discharge when the lance tube is fully extended and substantially simultaneously with the commencement of rotational movement thereof. In this manner, all of the discharged fluid is effectively used as a cleaning medium and the lance tube is subjected to the hot combustion zone for a minimum time period.
Generally, the wall deslagger of the invention comprises a frame structure mounting a rack housing, a rotary gear box, a valve and valve operator assembly. The frame structure also slidably supports a hollow, rotatable lance tube. A traversing rotary gear box is mounted to the rear end of the lance tube and includes a mechanical coupling with the rotary gear box of the frame structure whereby the lance tube may be rotated about its axis.
In accordance with a significant feature of the invention, a rack member is slidably associated with the lance tube and is capable of a predetermined limited longitudinal displacement relative to the lance tube. Ordinarily, the rack member is locked in a fixed relation to the lance tube and is in a driven engagement with a pinion mounted in the rack housing of the frame structure. Traverse movement to advance and retract the lance tube is achieved by operation of the pinion to drive the rack member. When the lance tube is in a fully extended position in the boiler, a mechanism releases the lock securing the fixed relation between the rack member and the lance tube thereby permitting continued advancing movement of the rack member. The rack member will then be able to advance to an operative engagement with the valve operating assembly to open the valve and discharge cleaning fluid to the lance interior after the lance has been fully extended. An appropriate limit switch is positioned such that the rack member activates the switch to commence a rotary drive to the lance tube substantially simultaneously with cleaning fluid discharge whereby the cleaning fluid reaches the nozzle at full pressure as rotation begins.
The cleaning cycle is terminated by a cam-activated switch. The cam is mounted on the lance tube and activates the switch after a full cleaning sweep by the lance tube. Closing of the switch activates the pinion to retract the rack member thereby closing the valve and retracting the lance tube to its inoperative position. The teachings of the inventive concept disclosed herein provide a highly reliable lance drive effectively coordinating lance movement and cleaning fluid discharge. The extensible rack arrangement affords a dependable, mechanically-straightforward means for imparting traverse motion to the lance tube while providing an accurately timed, advantageous fluid discharge.
For a better understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment of the invention and to the accompanying drawings.